The release said Birotte's "office is closing an investigation into allegations of federal criminal conduct by members and associates of a professional bicycle racing team owned in part by Lance Armstrong.

"The United States Attorney determined that a public announcement concerning the closing of the investigation was warranted by numerous reports about the investigation in media outlets around the world."

A spokesman for Armstrong's legal team on Friday said Armstrong was pleased.

"This is great news," attorney Mark Fabiani said a statement sent to Bicycle Retailer. "Lance is pleased that the United States Attorney made the right decision, and he is more determined than ever to devote his time and energy to Livestrong and to the causes that have defined his career."

The head of the U.S. Anti-Doping Agency, however, gave a more ambiguous statement.

“Unlike the U.S. Attorney, USADA’s job is to protect clean sport rather than enforce specific criminal laws. Our investigation into doping in the sport of cycling is continuing and we look forward to obtaining the information developed during the federal investigation,” said Travis Tygart, CEO of the Colorado Springs, Colorado-based organization.